Did you simulate it ? normally you get quite a bit of information from 
simulation. Not everyone has exactly the same board like you or the time 
to try to modify what you wrote.
I find the amount of logic used as really small, 45 LUTs ? Maybe it only 
generates a simple pattern...
Make a testbench to stimulate the clock and reset and see why it doesn't 
work. If it works meaning vsync and hsync have the proper period and 
polarity and you have some pixels to show... maybe the PINs are not 
correctly set or the clock is routed to some other pin... there are may 
possibilities... Do you have access to an oscilloscope ?

Maybe... did you have a look at what the code is supposed to do ?... I 
think you may be missing some ahem "sw" input.

thank everyone ... but i am sure my code and my pin assignment are 
correct ( i checked my pin assignment) ... i think the trouble is with 
this picture ... but how to do it ??
Finally , i would like to know how  to use code in the book to implement 
on kit de2-70 ... what do i need to change  ?

You could route your clock also to a Test-Output-Pin to check that it 
arrives in the FPGA. Next check the sync signals as already mentioned 
above. If they are ok generate a test-pattern as output to the 3 colors, 
if that is also ok route the real data to the output pins.

Your SYNC-Signals are High-Active,
but they should be Lo-Active. The
rest looks ok.

i programmed fbga with xp2 lattice chip to switch lvds from IPU and GPU 
on Macbook pro 15 2011. The screen resolution of 1440x900 and 1600x900 
is good. but 1920x1200 results are bad. I think the data and clk channel 
n and p output from the chip is not good. You let me ask how I write 
code to ensure that clk and data out are good